The use of hematoporphyrin derivative (HPD) in combination with red light is currently under investigation as an anti-cancer treatment modality. A major advantage of this therapy is the purported selectivity of tumor versus normal tissue response. Studies have been designed and are currently underway to establish HPD retention in tumor versus normal tissue in a murine model. An ovarian tumor model originating from a mouse has been used to determine the pharmacodynamics of HPD, optimization of HPD delivery, laser penetration, dose and timing of light and drug deliver into the peritoneal cavity. The use of different wavelengths of light is being studied on the ascites tumor model. Human xenografts from ovarian and lung are being studied in nude mice. Measurement of singlet oxygen is being studied to prepare the way for dosimetry. Dog toxicity to intracavitary HPD and laser light is being studied.